The present invention relates to a device for dispensing of a powdered drug preparation by inhalation. The device is in particular a multiple-dose device without propellant gas, equipped with a metering means which dispenses doses from a powder container. The device comprises two or more powder containers for different drug powders which can be inhaled as a combined medication. The device of the invention is useful, for example, in the treatment of asthma.
The administering of a powdered drug preparation by inhalation from an inhaler is known. Multiple-dose type powder inhalers comprising a flow container which holds the drug and a metering member which measures and dispenses a unit dose are also known, for example from patent publications GB 2165159, EP 79478, and EP 166294. In these devices, a series of dosing recesses are notched into the surface of a cylindrical metering member, and the said member is disposed in a chamber of precisely the same shape. When the metering member is rotated, the dosing recesses in turn will move first to a position in alignment with the powder container for being filled and thereafter to a position in alignment with the inhalation channel, where-upon a unit dose will fall by gravity from the dosing recess into the inhalation channel. Thereafter the dose of medicament is inhaled from the inhalation channel. These devices have the drawback that they make overdosing of the medicament possible by allowing the dispensing of a plurality of doses in succession into the inhalation channel, whereby a multiple dose may be drawn by one inhalation.
Attempts have been made to solve the above-mentioned problem by using dispensing systems in which the dosing recess will not be emptied into the inhalation channel by gravity but, instead, the dose of medicament is inhaled directly from the dosing recess, as disclosed in patent publications WO 92/00771 and WO 92109322. When the metering member is rotated, the dosing recesses will move first to a position in alignment with the flow container for filling, and then to the inhalation channel, which is shaped so that the dosing recess will be emptied under the effect of the air flow being inhaled, and thereafter, having rotated through a full 360xc2x0, back to a position in alignment with the flow container.
In the treatment of respiratory disorders it is often beneficial to administer a combination of drugs, e.g. combination of a bronchodilator and an anti-inflammatory drug to a patient. The devices described above are not capable to deliver more than one drug powder at a time. Even though it is in some cases possible to mix two or several drugs into an inhalable powder mixture to be administered simultaneously as a single dose, the incompatibility of the drug substances, interactions during storage or different aerosolization properties may often prevent the use of such drug mixture. Therefore, in order to inhale a combined medication the patient may have to inhale different drug powders from two powder inhalers. A multi-container powder inhaler has been earlier described in U.S. Pat. No. 5,524,613. However, this device is complex and requires a pressurized air source to aid the inhalation process. Furthermore, each powder is aerosolized in a common air channel, which does not take into account different aerosolization properties of the powders.
Therefore, there is a need for a simple low-cost multi-dose powder inhaler, which is able to deliver a combined medication by a single inhalation; and which takes into account different aerosolization properties of different medicament powders.
The present invention is related to a multi-dose powder inhaler capable of delivering a combined medicament, e.g. bronchodilator and an anti-inflammatory drug, simultaneously by a single inhalation. Rather than having a powder container for a mixture of the active ingredients, the inhaler comprises two powder containers from which doses needed for the combined administration are metered, brought to the air channel and inhaled simultaneously. Preferably the two containers contain different active ingredients. The active ingredients are in the separate containers, are brought to the air channel by separate dosing recesses and are mixed not earlier than in the air channel or in the respiratory tract of the patient during inhalation. Importantly, the inhaled air stream is conducted via two separate aerosolization channels, one for each medicament powder. Accordingly, the differences in the aerosolization properties of each medicament powder can be taken into account and each aerosolization channel can be designed according to the properties of each medicament powder.
The inhaler of the present invention is able deliver and deaggregate medicament powder from two or more dosing recesses simultaneously without the use of pressurized air even if used by a patient having reduced inhalation capacity.